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Argos Therapeutics Presents Research on the Development and Evaluation of Immunotherapies for HIV

-Abstracts Presented at Keystone Symposia on HIV Immunobiology-

Durham, NC- March 24, 2009 — Argos Therapeutics today announced the presentation of an abstract related to its Arcelis™ HIV immunotherapy program at the Keystone Symposia Global Health Series conference on HIV Immunobiology, held March 22 - 27 in Keystone, CO. The poster presentation details important research on the immunosuppressive properties of HIV, and how this research may influence the development of HIV immunotherapies.

The abstract, titled “The Immunosuppressive Properties of the HIV Vpr protein are Linked to a Single Highly Conserved Residue, R90,” details the study of IL-12 suppression by the HIV viral protein R (Vpr) in monocyte-derived dendritic cells (DC). IL-12 is a critical cytokine that is secreted by macrophages, monocytes and dendritic cells, and is suppressed by Vpr, implicating Vpr as an important virulence factor in HIV infection. Researchers hypothesized that the Vpr protein may be required to establish productive HIV infection, because it disables antigen presenting cells of the first infected mucosal tissues.

Analysis revealed that previously reported C terminal Vpr mutations do not alleviate the block of IL-12 secretion; however, a novel single conservative amino acid substitution, R90K, completely reverses the suppression. Further analysis demonstrated that R90 may not directly regulate the IL-12 pathway, but instead alleviates the suppressive effect through lowering Vpr intracellular levels. As a result, this study supports Vpr as an HIV virulence factor during HIV infection, and for the first time, provides a link between evolutionary conservation of Vpr and its ability to suppress IL-12 secretion by DCs.

“This abstract demonstrates Argos´ scientific leadership in understanding the immunobiology of HIV and provides important information for others who are developing HIV immunotherapies,” said Charles Nicolette, Ph.D., Chief Scientific Officer and Vice President of Research and Development at Argos Therapeutics. “The findings from our research on the Vpr protein should be considered in the design of future immunotherapies that incorporate Vpr as an antigen.”

The abstract was authored by: Irina Tcherepanova, Aijing Starr, Melissa Adams, Brad Lackford, David Calderhead, Don Healey, Mohamed-Rachid Boulassel, Jean-Pierre Routy and Charles Nicolette. The development of Argos´ Arcelis HIV immunotherapy program is part of the Company´s broad collaboration with Kyowa Hakko Kirin Co., Ltd.

About Argos Therapeutics, Inc.
Argos is an immunotherapy company developing new treatments for cancer, infectious and autoimmune diseases, and transplantation rejection. The Company has generated multiple platform technologies and a diverse pipeline of products based on its expertise in the biology of dendritic cells — the master switch that turns the immune system on or off. www.argostherapeutics.com

Jennifer Greenleaf-Conrad
MacDougall Biomedical Communications
(781) 235-3060

Jeff Abbey
Argos Therapeutics
(919) 287-6308

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